Cytochrome P sub(450) side-chain cleavage (P sub(450scc)) in the hen ovary. II. P sub(450scc) messenger RNA, immunoreactive protein, and enzyme activity in developing granulosa cells

• Published in: Biology of reproduction Vol. 45; no. 6; pp. 967 - 974
• Main Authors: Tilly, J L, Kowalski, KI, Johnson, AL
• Format: Journal Article
• Language: English
• Published: 01.01.1991
• ISSN: 0006-3363

Granulosa cells collected from developing, 6-8-mm follicles were found to contain extremely low but detectable levels of a single, 2.0-kb P sub(450scc) mRNA transcript, as well as immunoreactive P sub(450scc) protein (53 kDa). However, this protein was apparently incapable of converting 25-hydroxycholesterol to pregnenolone in a cell-free system. Preincubation of granulosa cells with ovine FSH or forskolin for 24 h rendered the cells capable of converting cholesterol precursor to pregnenolone during a subsequent 3-h incubation. Inclusion of the protein kinase C activator, phorbol 12-myristate 13-acetate (PMA), in the preincubation medium blocked the stimulatory actions of FSH and forskolin on the induction of P sub(450scc) activity; however, PMA-preincubation did not alter the ability of granulosa cells to convert exogenous pregnenolone to progesterone compared to vehicle-pretreated cells.